As a conventional technique of this kind, Patent Document 1 discloses the following laser processing method. Namely, a member for protecting a front face of a planar object to be processed is attached to the object, and the object is irradiated with laser light while using the rear face of the object as a laser light entrance surface, so as to form a starting point region for cutting generated by a modified region within the object along a line to cut. Subsequently, an expandable film is attached to the rear face of the object, and is expanded, whereby a plurality of parts generated by cutting the object from the starting point region for cutting acting as a start point are separated from each other. [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-1076